Dota – Why would a tower change target from a hero to creeps

The towers will attack enemies in this order:

1. Closest enemy unit or hero attacking a friendly hero with auto attack
2. Closest enemy unit or hero attacking the tower itself with auto attack
3. Closest enemy unit or hero attacking any friendly unit with auto attack
4. Closest enemy unit
5. Closest enemy hero
6. Closest enemy catapult

The tower will switch targets if:

7. The targeted enemy unit or hero dies
8. An enemy unit or hero targets a friendly hero
9. An enemy hero being attacked by the tower manually attacks a friendly unit or hero (in which case, the tower will select a new target based on the above priority order).

Last one is a weird mechanic that got greatly exploited during last few months,if you get targeted by the tower and click attack button and click on friendly creep the tower will start attacking the next target as if you got out of the attack range.It is getting its popularity since it enables you to attack tower with minimum interruptions(running away+running back from the tower range).To me it looks like a major bug since it makes no sense as a mechanic.

The thing that you mostly experience during the game is that you move inside the tower range (while it is attacking another unit), and then click attack on an enemy hero, which will make the tower attack you.

More discussion here and here.

Each time you or your teammates deal any damage to the enemy creeps (in this case by last hitting them) you slightly help your creep wave to push the lane towards the enemy tower.

The best place to farm is slightly in front of your towers range of attack,so you are close to safety but without tower interfering with the creeps.

To get creeps to fight there you will have to block your creeps movement as much as you can and then actively hit and deny your creeps as soon as they get under 50% HP to help enemy creeps push the lane closer to your tower.

Once you get the creeps to fight in that spot,in order to maintain that place each time you hit the enemy creep you should hit or deny one of your creeps too. This is known as maintaining lane or creep equilibrium.

There is also a chance that some invisible or hiding enemy hero is there trying to get EXP